Locating faults on messenger-call circuits



April 15, 1930., I G. w. JANSON 1,754,628

' LOCATING FAULTS'ON MESSENGER CALL CIRCUITS Filed Aljlg. .28, 1924 2 Sheets-Sheet April 15, 1930. G. w. JANSON LOCATING FAULTS ON MESSENGER CALL CIRCUIT Filed Aug.' 28, 1924 2 Sheets-Sheet 2 Patented Apr. 15, 1930 UNITED STATES PATENT OFFICE.

GEORGE W. JANSON, F NU'ILEY, NEW JERSEY, ASSIGNOR TO THE-WEBTERH UNION TELEGRAPH COMPANY, OF NEW YORK, N. Y., A CORPORATION 0]? NEW YORK LOCA'IING FAT JLTS 0N MESSENGER-CALL OJIRCUITS Application filed August 28, 1924. Serial No. 734,784.

This invention relates to a system and apparatus for line testing and for the locat1on of faults on a line, such as opens or grounds.

While the system is herein illustrated as applied to a messenger circuit, it obviously may be installed and applied to any other circuits, and it ma be used for various tests that are frequent y necessary to 'be made upon line circuits.

The system and apparatus which const tute my invention are designed to transmit over the line a distinctive tone and the systern is so arranged that the tonetransnnssion can be controlledby the lineman.

The operation of my system will he understood from the drawings and the following specification.

lln the drawings:

Fig. 1 illustrates my testing system as ap plied to a messenger call circuit in which there is an open;

Fig. 2 shows the conventional call box used in such circuits; I

Fig". 3 shows my line testing system as ap plied to the same circuit when a ground is on the circuit; and

ll ig. 4t shows the linemans apparatus used in testing. 0

My system is illustrated herein as applied to a messenger call circuit. Such call circuits comprise a loop in which a plurality of call boxes 11 are installed the ethos end of each arm ol the loop being provided with a relay 12 and the loop being connected to a ground ed source of current 13. The relay 12 operates circuit i l which includes a source oi. current 15 and a recorder 16. Such call cir cuits are provided with means for automatically indicating a fault on the line, and such means also indicate whether the fault is an open or a ground.

When a fault exists on such a messenger call circuit theline conductors and the ofiice apparatus are so divided that they operate as two distinctly separate circuits. The switch arms 17 are shifted to one position or the other, depending on whether the fault is an open or a ground, as shown in Figs. 1 and 3. My line testing system does not necessitate any change in the call circuit except for the installation of a jack 18 at the central oflice in one arm of the loop. My 3 stern comprises one set of apparatus 19wh1ch may be installed at the central ofiiceand provided with a plug 20 which may be inserted in the jack 18 at any time that it becomes necessary or desirable to test the line or to locate any faults therein. The central oflice apparatus 19 comprises an induction coil having a primary winding 21 and a secondary winding 22. The primary winding 21 is in a tone current generating circuit which, in addition to the winding 21, contains the buzzer 23, the source of current 24, the switch arm 25 with fixed contact points 26 and 2?, and the armature 28. In series with the secondary winding 22 of the induction coil is a relay 29 which is arranged to operate the armature 28. When the plug 20 is inserted into the jack 18, the relay 29 and the secondary winding 22 are insertedinto the line and in series with it. When the fault to be located is an open, the switch arm 25 is connected to the contact 26, as shown in Fig. 1, and when the fault to be located is a ground the switch arm 25 is connected to the contact 27, as shown in Fig. 3.

in addition to the apparatus installed at the central oilice, which is to be in series with a line in order to impose the tone current on the line, the lineman is provided with a portable apparatus illustrated in Fig. 4 which he carries along to apply to the line at any point. The linemans portion of the apparatus consists primarily of a telephone receiver 30 in series with a condenser 31, a ground connection 32, a manually operated switch 33, and resistance 34. The manually operated switch and the resistance are shuntcd across the telephone receiver and the condenser. .lhe apparatus is also provided with a pointed connecting rod for electrically connecting this apparatus with the line.

lln this system the application of the tone current to the line is controlled entirely by l the lineman at any point at which he may apply his portable testing set. The operation of the tone generating current is controlled by the relay 29 and the circuit for this relay is under the direct control of the lineman by means of his portable set. By alternately closing and opening the key 33, after he has applied the pointed rod 35 to the l ne, the lineman can first cause a tone to be 1mpressed on the circuit and then cause it to cease when he is making his tests as hereinafter described. He can thus know definitely that he is on one side or the other of a fault.

I shall now describe the operation of this system as it is used for the location of an open in the loop. As has already been stated herein above, if the fault to be located is an open the switch arm 25 in the tone current generating circuit is connected to the contact point 26. The plug 20 1s then 1nserted in jack 18, whereby the induction CQll winding 22 and the relay 29 are inserted in series with the line. In view of the fact that the line is open circuited at the faulty point, there is no current passing through the relay 29, and the tone current generating circuit is therefore open and no tone is transmitted through the line. The lineman now applies his apparatus to the line by means of the connecting rod 35 at the point 36. This completes the circuit of the relay 29 through the condenser and the telephone receiver. The condenser will draw a charge of current which will cause a click to be heard in the telephone receiver. 13 being the source of direct current, this will not energize relay 29 and the tone current generating circuit will remain open. If, now, the lineman closes switch 33, the relay 29 will be energized and the tone current generating circuit will close at 26,- 28, and the tone current will be imposed upon the line through the induction coil and will be heard at the telephone receiver by the lineman. This indicates to the lineman that he has an uninterrupted connection with the relay 29 and hence he concludes that the point 36 is positioned between the relay 29 and the fault. Now, had the linemans tests been applied on the other side of the fault, such as at the point 37, a similar click in the receiver would have been heard. Depressing the manually operated switch 33 would obviously have caused a current to flow from the source 13 to ground through the resistance 34, but the tone current generating circuit being on the opposite side of the open would not operate in such a way as to impose current upon the line. The tester will then know that the fault is between the point 37 and the relay 29.

\Vhen the fault to be located is a ground such as is shown at 40 in Fig. 3, the switch arm 25 is shifted to the position in which it connects with contact point 27. The apparatus 19 is connected to the line circuit as described heretofore. In view of the ground connection 40, there is a complete circuit from the source of current 13 through the relay 12 to the relay 29, winding 22 and ground 40.

The relay 29, therefore, stays energized and maintains the armature 28 against contact 26, whereby the tone current generating circuit is left ino erative. If, now, the line wire is opened as at 38, the armature 28 will be released and the tone current will be impressed upon the line which can be heard by the lineman applying the test set to the conductor at the point 41. This indicates to the lineman that he has uninterrupted connection from the point 41 to the relay 29, and that there is no fault or ground on that connection between the point 41 and the relay 29. He therefore knows that the point 41 is positioned between the relay 29 and the ground 40. At times, due to the fact that the hi h frequency alternating current generated y the tone current generating circuit may be transmitted to other wires by induction, this tone may be heard on both sides of the open line wire. If, for any reason, the lineman desires to know which of the conductors is directly connected to the central ofiice apparatus, he can determine that fact by applylng the test set to each of the wires with' the switch 33 closed. This constitutes nothing more than a repetition of the test for an open, as explained herein above. Now, if the lineman had chosen to apply his testing outfit to the point 39, then no tone would have been detected by the telephone receiver on either of the con uctors, for the ground 40 maintains the circuit of the relay 29 closed, and the relay 29 is maintained energized despite the open point 39, with the result that the tone gurrent generating circuit remains inoperaive.

It is often desirable to know which of the two conductors at any call box, or at any other point on a messenger call circuit, is connected at one of the oilice terminals. The apparatus described in this specification can now obviously be used for this purpose by connecting the relay and tone current generating circuit equipment at one of the terminals. If the loop, on investigation, normally carries current, the tone current generating circuit should be connected to the contact 27 of the relay 29; and if the loop is normally open or not connected to any source of current, the tone current generating circuit should be connected at the point 26. The circuit may then be opened at the testing point, and an attempt may be made to control the transmission of the tone current on each of the conductors. This control will only be effective over that conductor which is primarily connected to the relay 29.

While I have herein illustrated and described my testing system and apparatus as applied to a messenger call circuit, it is obvious to a person skilled in the art that such system and apparatus may be applied to any 4 other circuit and may be used for any other form of testing in addition to that of locating. faults.

I claim:

1. In a line testing system, an induction coil comprising a primary and a secondary winding, a tone current generating circuit connected to the primary winding, a relay connected to the secondary winding and controlling the operation of the tone current generating circuit, and means adapted to be connected to the line at any point for causing the relay to close said tone current generat- .ing circuit.

2. A line testing system employing a portable testing set responsive to a tone current comprising a tone current generating circuit, a relay connected in the line for controlling the operation of said tone current generating circuit in response to line conditions andv selective means in said tone current generating circuit for enabling the tone current to be generated either upon energization or deenergization of said relay.

3. A line testing system employing a portable testing set responsive to a tone current comprising a tone current generating circuit, a relay responsive to line and test set conditions for controlling said tone current gencrating-circuit, a primary winding in said tone current enerating circuit, an inductively dispose secondary winding in series with said relay and the line and selective means in said tone current generating circuit for enabling the tone current to be generated either upon energization or de-energization of said relay.

4. A line testing system for determining the location of open circuit or ground conditions in a line by means of a testing set responsive to tone current comprisin a relay responsive to line and test set con itions, a secondary winding in series with said relay and line, a two position armature for said relay, a tone current generating circuit controlled by said armature, selective means for enabling said armature to operate said tone current generating means in either position and a primary winding in said tone current generating circuit.

In testimony whereof I aifix m signature.

GEO. W. ANSON. 

